Field
Embodiments disclosed herein generally relate to a magnetic disk device employing a heat assisted magnetic recording (HAMR) head.
Description of the Related Art
To achieve a high signal-to-noise ratio (SNR) in a magnetic disk device that employs a HAMR head, one common technique used is to touch the stationary HAMR head on the disk and then back the head off of the disk. By utilizing this back-off technique, the required SNR can be obtained and the clearance height between the disk and the head may be estimated. Estimating or calculating the clearance of the head can be helpful to ensuring accurate performance of the HAMR head.
Additionally, a near-field transducer (NFT) may be utilized in a HAMR head to locally heat magnetic media having high coercivity during recording to lower the coercivity of the localized region. However, due to thermal expansion, the NFT may unintentionally touch down or contact the disk during operation or when employing the back-off technique. Since the NFT is typically significantly smaller than the other elements in the HAMR head, it can be difficult to determine when the NFT makes contact with the disk. When the NFT contacts the disk, the NFT may physically degrade, and consequently, the magnetic disk device may be damaged. Thus, knowing when the NFT touches down on the disk may prevent both the NFT and the magnetic disk device from degrading.
Therefore, an improved HAMR head that is able to detect NFT touchdown or contact is needed.